There are some YouTube vids on this. Essentially, you follow the steps to remove an old topper. Once the roller is free, give it an additional turn or two (YMMV) to tighten. Re-install the old topper as if it is a new topper.
The tricks are:
1. Two people make the job easier than one by a factor of four.
2. Line up the slot on the roller such that there is unimpeded access to the slot for easy removal and re-installation of the topper [on the roller side].
3. Before removing the topper, wedge a screwdriver in one of the holes in the end of the roller so that it does not unwind (they are very tightly sprung).
4. Use the screwdriver as a handle to tighten the roller spring. When you get it to your desired tightness, wedge it back where it was (against the side of the slide-out, prolly).
5. Spray the beads on the RV side and the roller side with WD40 -- makes the topper much easier to slide back into the slots.
Ken & Deb (WIT Club, FMCA, SKP, Harvest Hosts, and grateful volunteers with SOWERs)
2005 Winnebago Vectra 40FD w/400ISL and Allison 3000MH on Freightliner's Evolution chassis, Onan QD7500, 1000w Renogy solar, BlueOx tow gear, and 2015 Cherokee TrailHawk toad.